Calipers



(No Model.)

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UNITED STATES PATENT OFFICE.

JOSEPH RANDA, OF DETROIT, MICHIGAN.

CALIPERS.

SPECIFICATION forming party of Letters Patent No. 517,066, dated March 27, 1894.

Application filed May 31, 1893.

.To all whom it may concern:

Be it known that I, JOSEPH BANDA, a citizen of the United States, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Calipers, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates particularly to that form of beam caliper in which the sliding jaw carrles a Vernier.

The object of my invention is to provide simple and efficient means for its general use as an inside and outside caliper for all purposes to which that class of instruments is adapted: and further to specifically adapt it for a screw pitch gage, and to this end my invention has special reference to the graduation of the parts, the construction and arrangement of a combined adjusting and micrometer screw, and to the construction and arrangement of part-s, whereby the device operates as a screw pitch gage, which gives direct readings as conventionally expressed, all as more fully hereinafter described and .shown in the accompanying drawings, in which- Figure l is a front elevation. Fig. 2 is a rear elevation showing it as in operation as a screw pitch gage. Fig. 3 is an end elevation of the sliding jaw detached. Fig. 4 is a central section online 4 4 Fig. 3. Fig. 5 is an enlarged cross section of the ruler.

A is the beam.

B is the fixed jaw secured to the beam.

O is the Slide sleeved upon the ruler.

D is the movable jaw carried by the slide, and E E are openings in the front and rear face of the slide respectively for exposing the graduations of the beam. The beam has four scales placed respectively along the edges on both sides of the beam. The unit of each scale is the inch, but the subdivisions are respectively in eight, ten, twelve and fourteen parts for the dierent scales, the former two being-preferably placed on the front side and the latter two upon the rear side. The slide is sleeved upon the ruler by forming the recess F in the body of the slide, and closed by a plate G, let iny flush with the front face of the slide and secured in position by screws a. In this manner the slide may be ttcd very accurately upon the beam and by enlarging the Serial No. 476,129. (No model.)

recess a little upon both sides as shown in Fig. 3, the beam can wear only near the edges where it does not aect that portion of the graduations which appear in the openings of the slide.

To provide a slight friction to the moving of the slide, a small leaf spring H contained in a suitable recess F', is arranged to bear upon one edge of the beam. This recess is closed by the cover plate G and has inclined abutments b which hold the spring firmly in position against any accidental displacements.

To move the slide conveniently upon the beam the two outer corners have projections or horns I which form convenient hand holds, and to hold the slide in its adjusted position, a binding screw .I is tapped into the top of the slide so as to operate against the center of the spring H. In this way if the screw is tightened it bears only indirectly against the edge of the beam and therefore does not mar it. The marginal portions of the slide on top and bottom of the openings E E of the slide are beveled off. Upon these beveled edges, the graduations for the verniers are placed, each Vernier being constructedin the usual manner appropriate to the scale along which it 1s placed.

As the subdivisions on the four scales `are respectively in eight, ten, twelve and fourteen parts to the inch the verniers applied to these scales will thus enable me to measure respectively in sixty-four, one hundred, one hundred and forty-four and one hundred and ninetysix parts of an inch according to the scale I use. v

For purposes of still more accurate measurements, I have applied to the decimal scale, a micrometer attachment 'which gives the measurements to the one one-thousandth part ,of an inch.' To this end I cuty into the lower edge of the beam a screw thread c Fig. 5 which measures forty to the inch and into this engages a micrometer screw wheel K which has the same pitch and is carried by the slide. This micrometer' screw wheel is journaled in a sliding frame d which is supported in suitable guide bearings formed by a bracket e and by the movable jaw D. An adjusting screw is swiveled to the bracket e v and by means ef it the sliding frame d can be IOO . moVed, to carry the micrometer screw wheel into or out of engagement with the screw threaded edge of the beam the slide being suitably cnt away for the purpose. The micrometer screw wheel K has on one side a milled or knarle'd hub g for the purpose of turning it conveniently with the fingers, and on the other side it has a hub h which is circulnferentially graduated into twenty-five parts. Thus it will be seen that as it takes forty revolutions of the wheel K to move the slide one inch, each twenty-fifth part of a revolution will only move it one one-thousandth of an inch. W'ith this understanding the m0- dus operandi of using this mierometerattachmentneednotbefurtherexplained. Theserew wheel K also serves the general purpose of an adjusting screw, thus when it is desired to set the sliding jaw to a certain inside or outside measurement small errors in the adjustment of the slide by hand can be easily corrected by using the screw wheel to adjust the slide more accurately. The fixed and movable jaws are both alike, they project at right angles to the beam and when their inner faces are brought into contact with each other the zero point of the slide is at the zero point of the scales, thus the caliper gives direct readings for all outside measurements. To use the caliper for inside measurements as well, I make the lateral width of the jaws simple fractions of an inch. Thus the lateral width of the jaw at Z I make for instance equal to a quarter of an inch and at the reduced ends K of the jaws I makeit say one eighth of an inch. Thusin inside calipering only simple deductions have to be made.

The use of my caliper for a screw pitch gage I obtain in the following manner: I provide the jaws B l) with the supplementary taper jaws B D which extend in line with the jaws B D beyond the opposite end of the beam. Each jaw tapers toward its inner face at an angle of thirty degrees to a knife edge. In View of the common practice to construct V screw threads so as to have in cross section the form of an isosceles triangle, the jaws are thus adapted for calipering such screw threads by inserting the points of the jaws to the bottom of the threads, as shown in Fig. 2. This way of calipering threads is more accurate than the common way of measuring the distance on the outer edges of the screw threads, as it depends less on the practiced sight of an operator and also on account of the bottom threads of a screw being generally more perfect than the outer edges. It is also Very convenient in case of a broken off screw where often only one thread remains. In connection with this construction of the jaws B D I provide for a direct reading of the caliper measurements in number expressing the number of pitches to the inch, according to the standard in general use. To this end I have placed the following numbers on the graduation marks of the Vernier. On the second, fourth, seventh and last division lines of the Vernier, which measures fractions of one sixty-fourth of an inch I place the numbers 32, 16, 9 and S respectively. On the third, fourth, fifth, ninth and last division marks of the Vernier which measures in fractions of one one-hundredthsI place the numbers 34, 25, 20, 1l and l0 respectively. On the fourth, fifth, sixth, ninth, eleventh and last division marks of the Vernier, which measures in fractions of one one-hundredand-fortyfourths of an inch, I place the numbers 36, 30, 24, 18, 16, 13 and 12 respectively. On the fifth, seventh, ninth, thirteenth and last division marks of the Vernier, which measures in fractions of one one-hundred-andninety-sixths of an inch I place the numbers 4:0, 2S, 25, l5 and 11i respectively. The numbers thus placed on the graduation marks of the Vernier mean, that if any division mark bearing such a number corresponds with its scale, as in the ordinary way of calipering, the number indicates the number of threads to the inch. Thus for instance, in Fig. 2, where the caliper is shown applied for ealipering a screw thread, it will be seen that the last division mark on the upper Vernier' scale corresponds with its scale and the pitch of the screw measures thus twelve one-h undred-andforty-fourths of an inch, or expressed in the usual manner the screw has twelve threads to the inch and therefore the number l2 is found on this division mark. Ifin like manner by calipering another screw thread the fourth graduation mark on the same Vernier should correspond with its scale it would mean that the numberfiplaced on this fourth graduation indicates the number of threads of such screw to the inch. l-Iaving thus four scales measuring in fractions of sixty-four, one hundred, one hundred and forty-four or one hundred and ninety-six to the inch respectively, it is possible to pick out on one of the scales the exact measurements of almost any of the usual screw threads (on account of these four numbers containing all the primary divisors two, three, iive, and seven) and in this manner I provide for a direct reading of all usual screw threads between eight and forty to the inch. For instance if there are thirteen threads to the inch neither scale would give the accurate caliper of such a screw thread, as none of the four numbers sixty-four, one hundred, one hundred and forty-four and one hundred and ninety-six is divisible by thirteen. In such a case I take the nearest measurement, which would be found in this instance on the Vernier which indicates in fractions of one one-hundred-and forty-fourths of an inch, as one hundred and forty-four divided by thirteen is only a Very little more than eleven times and by placing the number 13 on the eleventh line of this Vernier I obtain a direct reading which is as readily found as any of the others. l

In using my caliper forgagin g screw pitches, it is obvious that for very fine threads two or more threads may be calipered at once and IOO ' movable jaw, a slide on the beam carrying the movable jaw and having a guideway thereimabracket on the slide having a guideway, an independently sliding frame supported in the guideways on the' slide and bracket, a screw threaded wheel journaled in said4 sliding frame adapted to engage the screw thread in the beam, and means for actuating the sliding frame, substantially as described.

2. In a caliper, the combination with the graduated beam having a screw thread in its edge and provided with a xed jaw and a movable jaw, a slide on the beam carrying the movable jaw, an independently sliding frame on the slide a screw threaded Vwheel j ournaled in said sliding frame adapted to engage the screw thread in the beam, and meansV for actuating the sliding frame, substantially asdescribed.

3.1m a caliper, the combination with the graduated beam having a screw thread in its edge and provided with a fixed jaw and a movable jaw, a slide on the beam carrying the movable jaw, an independently slidingframe on the slide, a screw threaded wheel journaled in said sliding frame adapted to engage the screw thread in the beam, and a screw for moving said sliding frame, substantially as described.

4. In a caliper, the combination with the graduated beam having a screw thread in its edge and provided with a fixed jaw and a movable jaw and a Vernier plate, a slide on the beam carrying the Vernier plate and movable jaw, a sliding frame on the slide, and a screw threaded micrometer wheel journaled in said sliding frame adapted to engage the 5o screw thread in the beam and having a series of graduated numerals arranged on one side, substantially as described.l

5. In a caliper, the combination with the graduated beam provided with a fixed jaw and a movable jaw, a slide carrying the movable jaw sleeved on said beam and provided with a recess therein having oppositely in.

clined walls, a spring in the recess having its ends abutting against thevinclined walls and its central portion adapted to bear against the beam, and means for varying the tension of the spring, substantially as described.

'6. In a beam caliper, the combination with the graduated beam and fixed jaw, of the slide carrying the movable jaw and formed withl JOSEPH RANDA.

Witnesses:

JAMEs WHITTEMORE, M. B. ODOGHERTY. 

